1. Field of the Invention
The present invention relates to a cleaning device for an image forming apparatus, and particularly to a cleaning device for removing residual toner from an image-carrying member using a cleaning blade.
2. Description of the Related Art
Conventional electrophotographic printers, such as image forming apparatus, have been provided with a photosensitive drum, an intermediate transfer member, and a cleaning device for cleaning the surface of the photosensitive drum. In such devices, electrostatic latent images are formed on the photosensitive drum and developed into toner images by a developer formed of toner. The toner image is then transferred from the photosensitive drum to the intermediate transfer member.
FIG. 1 shows an example of a cleaning device 140 provided in opposition to a photosensitive drum 131. The cleaning device 140 includes a housing 141, a cleaning brush 142, and a cleaning blade 143. An opening 141a is formed in the housing 141 opposite the photosensitive drum 131 for allowing communication between the inside and outside of the housing 141. The opening 141a is formed approximately in one side of the housing 141. The cleaning brush 142 and cleaning blade 143 are disposed in the opening 141a of the housing 141. The cleaning device 140 also includes a substantially cylindrical screw 144 disposed opposite the cleaning brush 142.
The cleaning blade 143 is disposed in contact with the photosensitive drum 131 with pressure. The cleaning brush 142 has a substantially cylindrical shape and is disposed upstream of the cleaning blade 143 with respect to the rotational direction of the photosensitive drum 131. The cleaning brush 142 opposes and contacts the photosensitive drum and rotates counterclockwise when the photosensitive drum 131 rotates in the clockwise direction. The cleaning blade 143 and cleaning brush 142 remove toner remaining on the photosensitive drum 131 after the toner image has been transferred to the intermediate transfer member. The cleaning brush 142 conveys toner that has been removed from the surface of the photosensitive drum 131 by the cleaning blade 143 toward the screw 144.
The cleaning device 140 having this construction prevents toner that has been removed from the photosensitive drum 131 from falling out of the opening 141a in the housing 141 and scattering.
As color electrophotographic printers have become more popular in recent years, it has become necessary to accommodate a plurality of image-forming units in a compact electrophotographic printer. To achieve this, the cleaning devices are disposed at positions directly above the respective photosensitive drum; the cleaning blades are placed in contact with the photosensitive drums near the top of the same; and the openings in the housings are formed in the bottoms thereof.
In this case, it is necessary to provide an auxiliary member for the cleaning device to prevent toner from leaking and scattering. For example, an air suction device may be provided for drawing air from the inside of the cleaning device. In Japanese patent application publications Nos. 2001-109212 and 2002-156879, an elastic plate is provided on the downstream end of the cleaning blade with respect to the rotational direction of the photosensitive drum and is held in contact with the photosensitive drum.
However, the actual process of discharging toner recovered by the cleaning blade is difficult to achieve by providing an air suction device or an elastic plate on the end of the cleaning blade for contacting the photosensitive drum. Further, if the inside of the electrophotographic printer becomes dirty by scattered or leaked toner or if toner clogs the cleaning device, frequent maintenance is necessary.